Field of the Invention and Related Statement
The present invention concerns a process for producing a cuprous oxide powder used, for example, as an a ship bottom paint, and, especially, as an antifouling pigment for ship bottoms.
For the production of cuprous oxide, the following methods have generally been known.
A. A method of mixing a copper powder and a copper suboxide (Cu.sub.2 O) hereinafter referred to as "cuprous oxide") powder, pressing and then heating the mixture in a tightly closed vessel at 100.degree. C. and producing cuprous oxide by interaction. PA0 B. A method of producing cuprous oxide by oxidizing a copper powder in an air flow by heating at 1,000.degree. C. PA0 C. A method of producing cuprous oxide by blowing oxygen enriched air into molten copper at 1240.degree. C. or higher, separating cuprous oxide in a molten state based on the difference of specific gravity, solidifying and then mechanically pulverizing the same. PA0 D. A method of producing cuprous oxide by electrolysis in a solution in which chlorine ions are present by using metal copper as an anode. PA0 E. A method of producing cuprous oxide by reducing copper ions in a solution with sodium sulfite or the like. PA0 F. A method of producing cuprous oxide by neutralizing a cuprous salt.
In the production methods for cuprous oxide described above, the methods A, B and C are dry production processes. However, the methods A and B have a drawback of requiring a long production time since a solid oxidizing reaction is utilized. In the method C, since oxygen enriched air is directly blown into the molten salt and copper is oxidized to form cuprous oxide, refractory materials of a furnace are abraded which deteriorates the purity of the products. In addition, cuprous oxide solidified from a solution at a high temperature and pulverized and further powderized into particles of about 10 .mu.m size results in a remarkable drawback of requiring large-powderizing facilities.
Meanwhile, since the methods D, E and F adopt a production process for cuprous oxide by a wet process and an electrolytic process, control for each of the steps is difficult. Further, such a wet process has difficulty in obtaining cuprous oxide particles suitable to an antifouling pigment.
The present invention overcomes such problems in the production of a cuprous oxide powder and it is an object of the invention to provide a process capable of producing a cuprous oxide powder suitable to a ship bottom paint, for example, an antifouling pigment, without requiring a large-scaled production facility, by simple steps, and efficiently and continuously.